I think it's translated as:
脂肪味
Sources:
http://news.sciencenet.cn/htmlnews/2015/7/323886.shtm
http://politics.people.com.cn/n/2015/0729/c70731-27376218.html
Baike has an article on it too, but that seems to be related to an earlier US finding related to the gene CD36.
Interestingly, your suggestion of 脂味 appears to be the preferred ...